The trend in digital cameras and digital imaging is toward smaller pixels to drive megapixel count upward or to enable smaller sensor areas. At the same time, improvements in speeds, sensitivity, and pixel numbers are desired. However, the reduction in size and increase in pixel numbers may not support the desired increase in speeds and sensitivity. Smaller sized pixels can suffer from many challenges. For example, smaller pixels may have lower sensing speeds or degraded resolution and color fidelity, and may have limited dynamic range when compared to larger pixels. Particularly in mobile sensors, the trend to shrink the pixel size and sensor area attempts to maintain performance through advanced processing. Reduced full well capacity, reduced quantum efficiency, and reduced photosensitivity of the sub-micron pixel detector array has greatly degraded signal-to-noise ratio (SNR) and dynamic range of the image sensor. In addition, higher cross-talk of the reduced pixel size results in image quality issues for example poor modulation transfer function (MTF) and color fidelity.
In digital imaging, the dynamic range of a complementary metal-oxide-semiconductor (CMOS) sensor may, at times, be insufficient to accurately represent outdoor scenes. This may be especially true in the more compact sensors which may be used in mobile devices, for example in the camera on a mobile telephone. For example, a typical sensor used in a mobile device camera may have a dynamic range of approximately 60-70 dB. However, a typical natural outdoor scene can easily cover a contrast range of 100 dB between light areas and shadows. Because this dynamic range is greater than the dynamic range of a typical sensor used in a mobile device, detail may be lost in images captured by mobile devices.